285/55R23 vs 275/60R23
Going from one to the other changes the overall height by +1.8 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 285/55R23 | 275/60R23 | Change |
|---|---|---|---|
| Overall height | 35.3" | 36.0" | +1.8 % |
| Sidewall | 6.17" | 6.50" | +5.3 % |
| Section width | 285 mm | 275 mm | -3.5 % |
| Circumference | 111.0" | 113.1" | +1.8 % |
| Revs per mile | 571 | 560 | -1.8 % |
| Axle height | 17.67" | 18.00" | +8.3 mm |
| Approved rim width | 8–10.5" | 7.5–10" | overlap 8–10" |
Both are approved on a rim 8" to 10" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 285/55R23. Fit 275/60R23 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 30.6 mph | +0.6 |
| 50 mph | 50.9 mph | +0.9 |
| 70 mph | 71.3 mph | +1.3 |
| 90 mph | 91.7 mph | +1.7 |
The odometer drifts with it. Ten thousand miles on the dial are really 10,184 on the road, so it under-counts by 184. At a true 70 mph the first turns 666 times a minute, the second 654.